NM_001267550.2:c.12957G>A

Variant names:

• chr2-178740276-C-T
• rs762330685
• NM_001267550.2:c.12957G>A

Variant summary

Our verdict is Likely benign. The variant received -6 ACMG points: 0P and 6B. BP4_Strong BP6 BP7

The NM_001267550.2(TTN):​c.12957G>A​(p.Ala4319Ala) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000465 in 1,613,494 control chromosomes in the GnomAD database, including 1 homozygotes. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Synonymous variant affecting the same amino acid position (i.e. A4319A) has been classified as Likely benign.

• Frequency:
  • Genomes: 𝑓 0.000092 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000042 (1 hom.)
• Consequence: TTN NM_001267550.2 synonymous
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:1 B:4
• Conservation: PhyloP100: 0.0450
• Publications: 1 publications found

Genes affected

TTN (HGNC:12403): (titin) This gene encodes a large abundant protein of striated muscle. The product of this gene is divided into two regions, a N-terminal I-band and a C-terminal A-band. The I-band, which is the elastic part of the molecule, contains two regions of tandem immunoglobulin domains on either side of a PEVK region that is rich in proline, glutamate, valine and lysine. The A-band, which is thought to act as a protein-ruler, contains a mixture of immunoglobulin and fibronectin repeats, and possesses kinase activity. An N-terminal Z-disc region and a C-terminal M-line region bind to the Z-line and M-line of the sarcomere, respectively, so that a single titin molecule spans half the length of a sarcomere. Titin also contains binding sites for muscle associated proteins so it serves as an adhesion template for the assembly of contractile machinery in muscle cells. It has also been identified as a structural protein for chromosomes. Alternative splicing of this gene results in multiple transcript variants. Considerable variability exists in the I-band, the M-line and the Z-disc regions of titin. Variability in the I-band region contributes to the differences in elasticity of different titin isoforms and, therefore, to the differences in elasticity of different muscle types. Mutations in this gene are associated with familial hypertrophic cardiomyopathy 9, and autoantibodies to titin are produced in patients with the autoimmune disease scleroderma. [provided by RefSeq, Feb 2012]

TTN-AS1 (HGNC:44124): (TTN antisense RNA 1) This gene encodes a non-coding RNA transcribed from the opposite strand to the titin gene. [provided by RefSeq, Aug 2016]

ACMG classification

Our verdict: Likely_benign. The variant received -6 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.76).
• BP6: Variant 2-178740276-C-T is Benign according to our data. Variant chr2-178740276-C-T is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 499097.
• BP7: Synonymous conserved (PhyloP=0.045 with no splicing effect.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_001267550.2. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TTN	NM_001267550.2	MANE Select	c.12957G>A	p.Ala4319Ala	synonymous	Exon 48 of 363	NP_001254479.2
	TTN	NM_001256850.1		c.12006G>A	p.Ala4002Ala	synonymous	Exon 46 of 313	NP_001243779.1
	TTN	NM_133437.4		c.12444G>A	p.Ala4148Ala	synonymous	Exon 46 of 192	NP_597681.4

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TTN	ENST00000589042.5	TSL:5 MANE Select	c.12957G>A	p.Ala4319Ala	synonymous	Exon 48 of 363	ENSP00000467141.1
	TTN	ENST00000446966.2	TSL:1	c.12957G>A	p.Ala4319Ala	synonymous	Exon 48 of 361	ENSP00000408004.2
	TTN	ENST00000436599.2	TSL:1	c.12681G>A	p.Ala4227Ala	synonymous	Exon 46 of 361	ENSP00000405517.2

Frequencies

GnomAD3 genomes AF: 0.0000920 AC: 14 AN: 152124 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.0000241

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.000458

Gnomad ASJ AF: 0.000288

Gnomad EAS AF: 0.000193

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000588

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.0000725 AC: 18 AN: 248376 AF XY: 0.0000520

Gnomad AFR exome AF: 0.0000646

Gnomad AMR exome AF: 0.000435

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.0000557

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.000166

GnomAD4 exome AF: 0.0000417 AC: 61 AN: 1461370 Hom.: 1 Cov.: 31 AF XY: 0.0000330 AC XY: 24 AN XY: 726990

African (AFR) AF: 0.0000299 AC: 1 AN: 33472

American (AMR) AF: 0.000514 AC: 23 AN: 44714

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26128

East Asian (EAS) AF: 0.000227 AC: 9 AN: 39682

South Asian (SAS) AF: 0.00 AC: 0 AN: 86256

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53196

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5764

European-Non Finnish (NFE) AF: 0.0000216 AC: 24 AN: 1111792

Other (OTH) AF: 0.0000663 AC: 4 AN: 60366

GnomAD4 genome AF: 0.0000920 AC: 14 AN: 152124 Hom.: 0 Cov.: 32 AF XY: 0.0000538 AC XY: 4 AN XY: 74304

African (AFR) AF: 0.0000241 AC: 1 AN: 41412

American (AMR) AF: 0.000458 AC: 7 AN: 15282

Ashkenazi Jewish (ASJ) AF: 0.000288 AC: 1 AN: 3472

East Asian (EAS) AF: 0.000193 AC: 1 AN: 5182

South Asian (SAS) AF: 0.00 AC: 0 AN: 4824

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10618

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 316

European-Non Finnish (NFE) AF: 0.0000588 AC: 4 AN: 68016

Other (OTH) AF: 0.00 AC: 0 AN: 2090

Alfa AF: 0.0000902 Hom.: 0

Bravo AF: 0.0000756

EpiCase AF: 0.00

EpiControl AF: 0.0000593

ClinVar

ClinVar submissions as Germline

Significance: Conflicting classifications of pathogenicity

Revision: criteria provided, conflicting classifications

Pathogenic	VUS	Benign	Condition
-	1	1	not provided (2)
-	-	1	Autosomal recessive limb-girdle muscular dystrophy type 2J;C1858763:Dilated cardiomyopathy 1G (1)
-	-	1	Cardiovascular phenotype (1)
-	-	1	TTN-related disorder (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.76
CADD	Benign	3.1
DANN	Benign	0.57
PhyloP100		0.045
Mutation Taster		=99/1	polymorphism

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Other links and lift over

dbSNP: rs762330685; hg19: chr2-179605003; COSMIC: COSV60421290; COSMIC: COSV60421290;